Copulative verbs, also known as linking verbs, "link" subjective complements and the original noun, basically renaming the noun. The copulative verb acts like an equal sign. Follow Yossarian the Grammarian as he explains several sentence...

This video lesson from Yossarian the Grammarian explains how to diagram a sentence that has subjective complements.

This video lesson from Yossarian the Grammarian gives a lesson on copulative verbs and subjective complements.